1. Industrial Field of Application
The present invention relates to a terminal connecting device.
2. Related Art
In a controller for controlling a motor of an electric vehicle, for example, a controller body is covered with a case and is thus protected. In order to connect the controller body to the motor, accordingly, it is necessary to lead out a terminal of the controller body to the outside of the case. The Unexamined Japanese Patent Application Publication No. Hei11-26050 has described an example of connection to be employed in that case.
As shown in FIG. 13, a flat conductor bent like an L-shape is used for a bus bar 1, a through hole 3A provided in a case 3 is caused to penetrate through a grommet 2 formed of an insulating material and the grommet 2 is fixed to the case 3 with a screw 7.
On the other hand, a terminal 5 of the bus bar and a terminal 4 on the controller side are fixed to each other with a bolt 6 in the case 3, and the other terminal of the bus bar which is not shown is lead out through the through hole of the case 3.
In this case, it is necessary to maintain insulating and sealing properties between the case 3 and the bus bar 1. Therefore, the grommet 2 formed of an insulating material is fitted in the through hole 3A of the case 3 by pressure.
Problems that the Invention is to Solve
According to such a structure, the sealing property should be improved between an opening 2A of the grommet 2 and the bus bar 1. More specifically, the flat conductor is used for the bus bar 1. Therefore, the ratios in vertical and transverse directions of the bus bar 1 are different from each other. Accordingly, when the grommet 2 (circular section) is fitted in the through hole 3A (circular) of a case 3, the fitting portions of the bus bar 1 and the grommet 2 do not uniformly come in close contact with each other because the grommet 2 has the compression ratios in the vertical and transverse direction which are different from each other. Thus, there is a fear for the sealing property.
The invention has been completed based on such circumstances and has an object to provide a terminal connecting device having a high sealing property.
In order to achieve the object, a first aspect of the invention is directed to a terminal connecting device for connecting both outer and inner terminals provided outside and inside a casing through a conductive bus bar inserted into a circular through hole opened on a wall surface of the casing, wherein a portion of the bus bar which passes through the through hole has a circular section, a hole wall of the through hole is attached, by pressure, to an outer periphery of the portion having the circular section, and a grommet formed of an insulating material which is to be sealed along a whole periphery of the hole wall is fitted and attached.
A second aspect of the invention is directed to the terminal connecting device according to the first aspect of the invention, wherein the bus bar is formed of a round bar member and an end side to be connected to the outer and inner terminals is provided with a terminal connecting portion crushed like a flat plate.
A third aspect of the invention is directed to the terminal connecting device according to the first or second aspect of the invention, wherein a contact portion is formed along a whole outer peripheral surface of the grommet, and when the bus bar provided with the grommet is to be inserted into the through hole, the contact portion is attached by pressure with being sealed to a hole wall of the through hole to attach a whole bus bar.
Function and Effect of the Invention
Invention of Claim 1
According to the first aspect of the invention, the bus bar to be inserted in the circular through hole provided in the casing has a circular section in the portion passing through the through hole. The grommet having the circular section is fitted and attached into the outer periphery of the portion having the circular section and the ratios in the vertical and transverse directions of the grommet are equal to each other. Accordingly, when the whole bus bar including the bus bar and the grommet is fitted in the through hole and is attached by pressure, the compression ratios of the grommet are equal to each other over the whole periphery. Consequently, the fitting portions of the external wall of the bus bar and the inner peripheral surface of the grommet and the fitting portions of the hole wall of the through hole and the outer peripheral surface of the grommet uniformly come in contact with each other. Consequently, a sealing property can be maintained along the whole periphery of the through hole of the casing.
Conventionally, a base material formed of a flat plate is used for the bus bar. Consequently, if the connecting portion of the terminals is to be constituted on both ends and they are to be set into positions twisted by 90 degrees, at least one of them should be formed by bending a predetermined expanded shape. In this case, a great deal of labor and time are required for the processing and yield is also deteriorated.
In this respect, according to the second aspect of the invention, the bus bar is formed of a round bar member. Therefore, the connecting terminal portions formed on both ends can be crushed by pressure in a free direction, and they can also be set easily in the twisted positions and the yield can also be enhanced.
Conventionally, the bus bar body including the bus bar and the grommet and the casing are fixed with a screw. According to the third aspect of the invention, however, a contact portion is formed along a whole outer peripheral surface of the grommet, and when the bus bar provided with the grommet is to be inserted into the through hole, the contact portion is attached by pressure with being sealed to a hole wall of the through hole to attach a whole bus bar without slip-off.
Accordingly, the screw for fixing is not required so that the number of parts can be reduced and an excellent assembling property can also be obtained.